Characterizing the Placebo Response in Adults With ADHD.

Area of Science:

• Psychiatry
• Clinical Psychology
• Pharmacology

Background:

• Pharmacological trials for Attention-Deficit/Hyperactivity Disorder (ADHD) frequently report high placebo response (PR) rates.
• Understanding the characteristics of PR in adult ADHD is crucial for accurate trial interpretation.

Purpose of the Study:

• To characterize placebo response in adults diagnosed with ADHD.
• To investigate the temporal patterns and consistency of placebo response in this population.

Main Methods:

• Retrospective cohort analysis of 140 adult ADHD participants in the placebo arm of a 6-week clinical trial.
• Utilized Conners' Adult ADHD Rating Scale (CAARS) and Adult ADHD Self-Report Scale (ASRS) for assessment.

Main Results:

• Significant pre-post changes in both CAARS and ASRS scores were observed in placebo-treated adults.
• Less than half of participants exhibited early and persistent PR; nearly 50% showed variable, inconsistent PR.
• Placebo response was prominent on both self-report and investigator-rated scales.

Conclusions:

• Investigator ratings as a primary endpoint may not fully mitigate placebo response in adult ADHD trials.
• The variable nature of PR in approximately half of the participants suggests potential unreliability in determining treatment efficacy.
• Further research is needed to address the impact of variable placebo response on clinical trial outcomes.